Delayed Untwisting. The Mechanistic Link Between Dynamic Obstruction and Exercise Tolerance in Patients With Hypertrophic Obstructive Cardiomyopathy

Jianwen Wang, John M. Buergler, Kumuthavally Veerasamy, Yelena P. Ashton, Sherif F. Nagueh

Research output: Contribution to journalArticle

48 Scopus citations

Abstract

Objectives: We sought to determine the mechanisms linking dynamic obstruction and exercise tolerance in patients with hypertrophic obstructive cardiomyopathy (HOCM). Background: Patients with HOCM have reduced exercise tolerance. However, the association between dynamic obstruction and peak oxygen consumption (Vo2max) is weak. Methods: We enrolled 25 patients with HOCM, 20 with hypertrophic cardiomyopathy (HCM), and 20 normal control patients. Two-dimensional, Doppler, strain, and left ventricular (LV) twist mechanics by speckle tracking echocardiography were obtained. The 25 HOCM patients had left heart catheterization, and 16 were re-examined after septal reduction. Results: Deformation measurements were the lowest in HOCM patients and increased (p < 0.05) after septal reduction. Twist and untwisting rate were not different between patients with HCM and control patients, but untwisting was significantly delayed in HCM patients and longest in HOCM patients. The delay related well with LV end-diastolic pressure (r = 0.76) and volume (r = -0.73), and Vo2max (r = -0.75, all p < 0.01). After septal reduction, untwisting occurred earlier and accounted for the increase in end-diastolic volume (r = 0.65), and Vo2max (r = 0.74, both p < 0.05). Conclusions: Dynamic obstruction leads to delayed untwisting in HOCM, which accounts well for the increased LV filling pressures, the reduced LV volumes, and Vo2max. After septal reduction, untwisting occurs earlier and leads to an improvement in LV filling and exercise tolerance.

Original languageEnglish (US)
Pages (from-to)1326-1334
Number of pages9
JournalJournal of the American College of Cardiology
Volume54
Issue number14
DOIs
StatePublished - Sep 29 2009

Keywords

  • diastole
  • exercise
  • hypertrophic cardiomyopathy
  • mechanics

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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